Posts Tagged ‘track 29’

[Editor’s note: Since moving to Washington, DC, neigh on 7 years ago, I have been fascinated by the system of street names used in the nation’s capital. There’s your normal east-west, north-south grid sectioned into cardinal quadrants in the NW, NE, SW, and SE directions, and then all the state streets, often large Avenues, named after the 50 first-order administrative units that form these United States. The above map shows where these are (some are tiny!), and the entire post, from GreaterGreaterWashington and 29Tracks, has more maps and dialog including a tidbit about the 1st thru 3rd rings being based on number of syllables and the 4th ring based on plants. Thanks Laris!]

Visitors and residents of Washington, DC know, to one degree or another, about the city’s street naming conventions. Most tourists know that we have lettered and numbered streets. And to some degree, they know there is a system, but it doesn’t stop them asking us directions. But most out-of-towners and even many residents don’t understand the full ingenuity of the District’s naming system.

Washington is partially a planned city. The area north of the Potomac and Anacostia Rivers and south of Florida Avenue (originally Boundary Street) is known as the L’Enfant City. This area of Washington was the original city of Washington, laid out by Pierre L’Enfant and Andrew Ellicott. It is comprised of a rectilinear grid with a set of transverse diagonal avenues superimposed. Avenues frequently intersect in circles or squares, and the diagonals create many triangular or bow tie-shaped parks.

Washington is the seat of government of a nation. Believing that the structure of the government should inform the structure of the city, L’Enfant centered the nascent city on the Capitol, home of the Legislative (and at the time, the Judicial) branch of the government, the one the framers held in highest esteem. From this great building radiate the axes of Washington. North and South Capitol Streets form the north-south axis; East Capitol Street and the National Mall form the east-west axis. These axes divide the quadrants.

The axes also provide the basis for the naming and numbering systems. Lettered streets increase alphabetically as they increase in distance both north and south of the Mall and East Capitol Street. Numbered streets increase in number as they increase in distance both east and west of North and South Capitol Streets.

Even though subways are a fuel-efficent way to move people around congested urban areas, Americans make poor use of them, probably because they are poorly funded and often don’t travel where we want to go. Right now, of the five most-used subway systems in the country, only New York City’s attracts as many riders as the five largest foreign subway systems.

[Editor’s note: Washington DC has the second busiest subway system in the US after New York city. This series of visual diagrams show the network’s topology and how to optimize routing to achieve a better level of service (quicker train frequency). Note how the time scale has been reduced to modular 12, easy to understand as a train every 2 to 6 minutes based on the number of colored lines thru each subway station.

DC’s metro rail subway is convenient and affordable. But with more people using transit every year, the system is beginning to show signs of strain (heck, it’s over 30 years old now!). The federal gov’t just gave one of the last nods to construct a new line (dubbed the “Silver”) connecting downtown DC to Dulles International Airport and farther out into the exurbs. But this does little to alleviate crowding on the original 5 rail lines .

How to squeeze the most capacity out of existing tunnels and switches? These excellent maps from Track 29 chart the current system and show how it might be tweeked to optimize the flow of passengers from point A to point B primarily on the Orange line, the most overcrowded, where a switching problem reduces train frequency thru the downtown central business district (CBD).]

The first diagram represents WMATA’s current service pattern during rush hours. Colors represent each of the subway routes. More lines along a colored route represent better (more frequent) service. [Ed: not all stations shown, based on "rush" peak service.]

Based on the 135 second headway, WMATA can run 5 trains through a given segment of track every 12 minutes. Each the diagrams below represents a 12 minute interval during rush hour. Each of the lines on the diagram represents a train in each direction. Therefore, a trackway with two lines (like between Stadium Armory and Largo) represents a headway of 6 minutes–12/2. In other words, you’ll be waiting for a train for up to 6 minues. While on the Red line it would only be 2.5 minutes. [Ed: map seems to undercount Green line service.]

There are several choke points in the system, including at the Roslyn tunnel where the Orange and Blue lines converge and travel under the Potomac River into the District of Columbia.

The chief limitation for the Orange Line, as you can see here is the 4 minute headway on the Vienna-Rosslyn segment. Adding one train would reduce headways to 3 minutes and would add a capacity of 1000-1400 passengers for every 12 minute period. Any additional capacity is sorely needed, but the segment of track between Rosslyn and Stadium Armory is essentially at capacity.

Hence the so-called “Blue Line Split.” Here’s what WMATA is proposing: [Ed: WMATA runs the Metrorail subway in DC.]

This results in better service on the Orange line, and equivelent service on the Blue, except for Arlington Cemetary station primarily used by tourists (there are no homes or offices at that station). Many Blue line riders actually need to transfer at Metro Center or L’Enfant stations or get to eastern downtown faster, so this may actually be a boon for them, too.

But, while that squeezes extra service, the naming convention of the lines becomes confused. Some propose renaming / rerouting the Blue and Yellow lines like so (below). This map reflects this and planned Silver line service.

Greater Greater DC has a full discussion of adding even more commuter rail service to the nation’s capitol.